With the continuous development of air conditioning technology and strengthening of people's environment protection consciousness, a heat recovery multi-split system is more and more popular in the market, and a two-pipe heat recovery multi-split system is one of the dominant heat recovery multi-split systems on the current market. When the two-pipe heat recovery multi-split system operates under a main cooling mode, a gas-liquid two-phase refrigerant with a certain degree of dryness is input into an indoor unit from an outdoor unit. In theory, a constant value control of the dryness of the gas-liquid two-phase refrigerant may be realized as long as an outdoor heat exchanger is controlled fine enough such that better effects of both of cooling and heating indoor units may be achieved. However, in practice, it is often the case that there is more liquid than gas or more gas than liquid.
In the related art, in order to make both of the cooling and heating indoor units may achieve good effects, a liquid refrigerant needs to be distributed to a cooling indoor unit and a gaseous refrigerant needs to be distributed to a heating indoor unit according to an appropriate proportion, and the distribution of refrigerants of the cooling and heating indoor units is usually realized by adjusting a pressure difference between the front and back of a first electronic expansion valve in the distribution device. However, the pressure difference between the front and back of the first electronic expansion valve in a distribution device is controlled according to a certain value or within a certain range, because such a control strategy is often performed based on data acquired on the basis of various simulation experiments by manufacturers, which not only has a limited adjustment range, but also is not smart enough, and hard to make the system to operate in a better status.